JPH0312655A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic sensitive body which exhibits a good sensitivity, excellent environmental resistance and high durability by incorporating an alkyd resin and melamine resin as a binder into a charge generating layer. CONSTITUTION:The alkyd resin and melamine resin are incorporated as the binder into the charge generating layer of the separated function type electrophotographic sensitive body formed by laminating at least the charge generating layer and charge transfer layer on a conductive substrate. While any alkyd resins known heretofore are usable as the alkyd resin, the oil-free alkyd resin is more preferably used. A butylated melamine resin is adequate as the melamine resin. the electrophotographic sensitive body which is not deteriorated in the characteristics of the photosensitive body, such as electrostatic chargeability, and exhibits the good sensitivity in spite of long-term repetitive use and has the high durability and good preservable property is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor that exhibits good sensitivity, excellent environmental resistance, and excellent durability. Regarding photoreceptors.

[Conventional technology]

Inorganic materials such as selenium, cadmium sulfide, and zinc oxide have been conventionally known as photoconductive materials for electrophotographic photoreceptors. However, these inorganic materials do not necessarily satisfy the characteristics such as photosensitivity, thermal stability, and durability required for electrophotographic photoreceptors, as well as manufacturing conditions. For example, selenium has drawbacks such as being easily crystallized by heat, dirt, etc. and having properties deteriorate easily, and requiring care in handling such as manufacturing cost, impact resistance, and toxicity.

Photoreceptors using cadmium sulfide have poor moisture resistance and durability, and also have problems such as toxicity. Zinc oxide also has the disadvantage of poor moisture resistance and durability.

For electrophotographic photoreceptors using these inorganic photoconductive materials,
Photoreceptors using organic photoconductive materials are being actively researched and developed due to their light weight, ease of film formation, manufacturing cost, and wide availability of varieximin as an organic compound6. is a photoreceptor containing polyvinylcarbazole and 2,4,7-dolinitro-9-fluorenone described in Japanese Patent Publication No. 50-10496, Japanese Patent Publication No. 1988-10496
A photoreceptor in which polyvinyl carbazole is sensitized with a biryllium base dye as described in Japanese Patent No. 25658, or a photoreceptor having a eutectic complex as a main component has been proposed. However, these photoreceptors do not have sufficient sensitivity and durability.

Therefore, in recent years, a functionally separated type photoreceptor in which a charge generation layer and a charge transport layer are separated has been proposed, and
A photoreceptor comprising a combination of chlordiane blue and a hydrazone compound as described in JP-A-53-133445, JP-A-54-21728, and JP-A-54-22834 with a bisazo compound as the charge generating substance.
As described in the publication, the charge transport material is JP-A-58-198.
043 JP-A-58-199352 and the like are known.

However, these function-separated photoreceptors are still unsatisfactory, especially in terms of durability.In recent years, as demands for durability have increased more and more, ensuring charging stability has become an issue that cannot be ignored. . That is, if the charging property is decreased, it causes a decrease in the image density of a copy in a copying machine, and in a laser printer using a one-reversal development method, it causes a decrease in image quality such as background staining. In order to solve these problems,
It has been proposed to provide an intermediate layer between the conductive substrate and the photosensitive layer. However, when a high-resistance material with high barrier properties is used for the intermediate layer in order to stabilize the charging property, although the charging property is improved, there are disadvantages in that the photosensitivity decreases and the residual potential increases. Furthermore, if a material with relatively low resistance that does not increase the residual potential is used, charging stability will be insufficient.

On the other hand, the charge generation layer is basically composed of an organic pigment as a charge generation substance and a binder as a binder. Examples of such binders include polyvinyl butyral (Japanese Unexamined Patent Publication No. 58-105154), fatty acid cellulose ester (Japanese Unexamined Patent Publication No. 58-166353), and acrylic resin with a Tg of 70°C or less and an acid value of 10-40 (unexamined Japanese Patent Publication No. 58-105154). Kaisho 58-192
No. 040), a mixture of a resin with a Tg of 70°C or lower and a resin with a Tg of 75°C or higher (JP-A-58-193549), 1! A resin-solvent system with lower compatibility is added to the system of a chemical-generating substance-resin-solvent and re-dispersed (Japanese Patent Application Laid-Open No. 1983-1999)
No. 12646), polyvinylpyrrolidone (Japanese Patent Application Laid-open No. 12646-
No. 113140), polyvinyl formal (Japanese Patent Application Laid-open No. 61
-235844) and the like. However, the conventional view of the binder in the charge generation layer is that it is a binding agent for the charge generation substance, and it is not true that it provides dispersibility, dispersion stability, and adhesion to other layers. Therefore, conventional functionally separated electrophotographic photoreceptors are not sufficient in terms of potential characteristics such as residual potential and potential fluctuation.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned circumstances of the prior art, and its object is to exhibit good sensitivity.

An object of the present invention is to provide an electrophotographic photoreceptor having excellent environmental resistance and high durability.

Another object of the present invention is to provide a photoreceptor for a semiconductor laser printer, and also to provide a functionally separated photoreceptor that is easy to manufacture.

[Means to solve the problem]

According to the present invention, in a functionally separated electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated on a conductive support, the charge generation layer contains an alkyd resin and a melamine resin as a binder. An electrophotographic photoreceptor is provided.

The electrophotographic photoreceptor of the present invention contains an alkyd resin and a melamine resin as a binder in the charge generation layer, so deterioration in charging property due to repeated use is suppressed, and the electrophotographic photoreceptor has a long life, high reliability, and high sensitivity. It is something.

As the alkyd resin, any conventionally known alkyd resin can be used, but oil-free alkyd resins are preferably used. Commercial products of such resin include Veraflite M-6401-50, M-6402-50, M-600.
3-60, M-6005-60, 46-118, 46-
119,52-584゜M-6154-50,M-63
01-45, 55-530, 54-707, 46-16
9-3, M-6201-40-IN, M-6205-5
0,54-409 (trade name of Dainippon Ink & Chemicals MLL OOL-free alkyd resin), Nispel 103.11
0.124,135 (trade name of oil-free alkyd resin manufactured by Hitachi Chemical Co., Ltd.).

Melamine resins used as a component of the binder together with alkyd resins include butylated melamine resin, methylated melamine resin, butylated benzoguanamine resin, and methylated benzoguanamine resin.

Among them, butylated melamine resin is preferred. Commercially available products include Super Beckamine G-82.
1-60, TD-139-60, L-110-60,4
7-507-60, L-145-60, L-118-6
0 (trade name of butylated melamine resin manufactured by Dainippon Ink & Chemicals ■), Melan 2000 and Melan 8000 (trade name of butylated melamine resin manufactured by Hitachi Chemical ■), and the like.

The ratio of alkyd resin and melamine resin used is 1 by weight.
00:10-100:50 preferably 100:60-1
It is 00:20.

If the ratio exceeds 100:50, sensitivity will deteriorate, and if it is less than 100:50, charging properties will be poor, making it impossible to achieve the intended purpose of the present invention.

Next, each constituent material used in the present invention will be explained.

The purpose of the conductive support is to supply charges of opposite polarity to the charged charges to the substrate side.

It is possible to use a material that has an electrical resistance of 10' Ωcm or less and can withstand the conditions for forming the charge generation layer, the charge transfer layer, and the undercoat layer. Examples of these are:

The surfaces of electrically conductive metals and alloys such as AQ, Ni, Cr, Zn, and stainless steel, inorganic insulating materials such as glass and ceramics, and organic insulating materials such as polyester, polyimide, phenol resin, nylon resin, and paper are vacuum-treated. AQ, Ni, Cr, Zn, stainless steel, carbon s by methods such as vapor deposition, sputtering, and spray painting.
Examples include those coated with an electrically conductive material such as -SnO, In, 03, etc. and subjected to conductive treatment.

Further, the charge generation layer of the present invention is composed of a charge generation substance, a binder made of an alkyd resin, and a melamine resin, as described above.

It is appropriate to use the binder in a total amount of 0.01 to 200 parts by weight per 100 parts by weight of the charge generating substance.
Preferably it is 1 to 50 parts by weight.

Examples of the charge generating substance include CI Pigment Blue 25 [Color Index (CI) 21180],
CI Pigment Red 41 (CI 21200),
C.I. Acid Red 52 (CI 45100), C.I. Basic Red 3 (CI 45210), and a phthalocyanine pigment having a porphyrin skeleton,
Azulenium salt pigments, squalic salt pigments, azo pigments with a carbazole skeleton (described in JP-A-53-95033), azo pigments with a stilstilbene skeleton (
(described in JP-A No. 53-138229), azo pigments having a triphenylamine skeleton (described in JP-A-53-1325)
47), azo pigments having a dibenzothiophene skeleton (described in JP-A No. 54-21728), azo pigments having an oxadiazole skeleton (described in JP-A-54-1
No. 2742, a), an azo pigment having a fluorenone skeleton (described in JP-A No. 54-22834), an azo pigment having a bisstilbene skeleton (described in JP-A No. 54-177)
33), an azo pigment having a distyryloxadiazole skeleton (described in JP-A No. 54-2129), an azo pigment having a distyrylcarbazole skeleton (described in JP-A-54-17734) , triazo pigments having a carbazole skeleton (described in JP-A-57-195767 and JP-A-57-195768), and CI Pigment Blue 16 (CI 74100).
Phthalocyanine pigments such as Sea Eye Butt Brown 5
(CI 73410), Sea Eye Bat Die (CI 7
3030), etc., Argo Scarlet B
(manufactured by Violet), Indus Thread Scarlet R (
Organic pigments such as perylene pigments such as those manufactured by Bayer AG can be used.

Among these charge-generating substances, azo pigments are particularly preferred, and among azo pigments, disazo pigments and trisazo pigments shown below are most preferred.

Specific examples of azo pigments are shown below.

The thickness of the charge generation layer is suitably about 0.05 to 5 pm, preferably about 0.1 to 2 pm.

The charge generation layer can be formed by dissolving or dispersing the binder and charge generation substance in a suitable solvent, applying the solution, and drying the solution. As a solvent, benzene, toluene,
Xylene, methylene chloride, dichloroethane, monochlorobenzene, dichlorobenzene, ethyl acetate, butyl acetate, methyl ethyl ketone, dioxane, tetrahydrofuran, cyclohexanone, methyl cellosolve, ethyl cellosolve, and the like can be used alone or in combination.

The charge transport layer can be formed by dissolving or dispersing a charge transport substance and a resin binder in a suitable solvent, coating the solution on the charge generating layer, and drying the solution. Moreover, a plasticizer, a leveling agent, etc. can also be added if necessary.

Charge transport substances include poly-N-vinylcarbazole and its derivatives, poly-γ-carno(zolylethylglutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole). Derivatives, imidazole derivatives, triphenylamine derivatives, 9-(P-diethylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenyl Examples include electron-donating substances such as stilbene derivatives.

As a resin binder, polystyrene, styrene-7
Acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer,
Polyvinyl acetate, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene.

Examples include thermoplastic or thermosetting resins such as poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, urethane resin, and phenol resin.

As the solvent at this time, tetrahydrofuran, dioxane, toluene, monochlorobenzene, dichloroethane, methylene chloride, etc. can be used.

The thickness of the charge transport layer is 5 to 30 mm. , preferably lO~2
Approximately 5- or so is appropriate.

The photosensitive layer of the electrophotographic photoreceptor of the present invention can be of a positively charged type or a negatively charged functionally separated type by combining a charge generation layer and a charge transport layer.

In the case of a negatively charged type, a charge generating layer containing a charge generating substance and a binder is formed on the substrate, and a charge transporting layer containing a charge transporting substance and a binder is formed thereon. When forming a mold, the charge generation layer and the charge transport layer are laminated in reverse order.

Note that a charge transporting substance may be contained in the charge generation layer, and particularly in the case of a positively charged structure, the sensitivity is improved.

Furthermore, in the present invention, a subbing layer may be provided between the conductive support and the photosensitive layer, if necessary. The subbing layer is a layer intended to prevent light interference in the photosensitive member for printers. Such an undercoat layer is constructed by dispersing conductive powder such as tin oxide or antimony oxide and white pigment such as zinc oxide, zinc sulfide or titanium oxide in a thermosetting resin such as the one below. The light-absorbing subbing layer is constructed by dispersing a conductive light-absorbing pigment such as carbon, various metals, and/or a light-absorbing organic pigment in a similar thermosetting resin. The thermosetting resin used here is, for example, a compound containing a plurality of active hydrogens (hydrogens such as -OH group, -NH, group, -NH group, etc.), a compound containing a plurality of incyanate groups, and/or It is obtained by thermally polymerizing a compound containing a plurality of epoxy groups. Examples of compounds containing multiple active hydrogens include polyvinyl butyral, phenoxy resin,
Examples include phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene gelicol, acrylic resin containing active hydrogen such as hydroxyethyl methacrylate group, and polyamide compounds such as alcohol-soluble nylon and methylol nylon. Examples of compounds containing multiple incyanate groups include tolylene diisocyanate,
Examples include hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof; examples of compounds having a plurality of epoxy groups include bisphenol A type epoxy resin; examples of polyamides include 8-nylon.

The undercoat layer is formed by applying a solution in which the above-mentioned components are dissolved or dispersed onto a substrate and thermally polymerizing the solution at 50 to 200°C.

Note that the thickness of this undercoat layer is suitably 0.05 to 20 μs. Further, the weight ratio of the conductive powder, the white pigment, and the thermosetting resin is suitably 2 to 6/1 to 572 to 6, and the weight ratio of the light absorbing pigment to the thermosetting resin is 4 to 6/1. 9/1
-6 is appropriate.

It is also possible to provide a protective layer, a coating layer, or an intermediate layer on the photosensitive layer in order to protect the photosensitive layer from mechanical abrasion and exposure to ozone during charging. Adhesive layers can also be provided to improve adhesion between the layers.

〔Effect of the invention〕

Since the electrophotographic photoreceptor of the present invention has the above-mentioned structure, the photoreceptor properties such as charging properties do not deteriorate even after repeated use over a long period of time, and it has high durability and good storage stability, so it has extremely practical value. It's expensive.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 An aluminum cylinder with a diameter of 801w1 and a length of 340m was used as a support, and on this aluminum cylinder.

A subbing layer coating solution consisting of 90 g of polyamide resin (product name: CM8000, manufactured by Toshi ■), 1540 g of methanol, and 660 g of butanol was applied by dip coating, and dried by heating at 120°C for 10 minutes to form a subbing layer with a film thickness of 0.3-. Layers were provided.

Next, apply the following charge generation layer coating liquid (A) on this undercoat layer.
Spray coat it, heat dry it at 130℃ for 20 minutes,
A charge generation layer having a thickness of 0.1- was provided.

[Coating liquid for charge generation layer (A)]

Disazo pigment & 114.3g, methyl ethyl ketone 16
5 g was dispersed in a ball mill for 10 days. Next, n-butanol was added to 139 of this dispersion, and the mixture was further dispersed for 24 hours. Take out 6 g of this dispersion, and take out an alkyd resin solution (alkyd resin: trade name: Beccolito 6401-50, manufactured by Dainippon Ink & Chemicals, Solvent: methyl ethyl ketone) with a solid content concentration of 1°2 and a weight of 2. and solid content concentration 0
．． 21 g of a melamine resin solution (melamine resin: trade name: Nis-Perbeckamine G-821-60, Dainippon Ink Chemical Industry ■Il: solvent: n-butanol) of 09% by weight was added dropwise and diluted to form a charge generation layer coating liquid ( A).

Further, on this charge generation layer, a charge obtained by dissolving 330 g of a charge transporting substance represented by the following formula (1) and 365 g of polycarbonate resin (trade name: Panlite C-1400, manufactured by Konjin) in 3160 g of methylene chloride was applied. A transport layer coating solution was applied by dip coating and dried by heating at 130° C. for 20 minutes to form a charge transport layer having a thickness of 22°, thereby preparing an electrophotographic photoreceptor of the present invention.

Comparative Example 1 A sample was prepared in the same manner as in Example 1, except that the charge generation layer coating liquid (A) used in Example 1 was replaced with the charge generation layer coating liquid (B) below.

[Coating liquid for charge generation layer (B)]

Disazo pigment & 114.3g, methyl ethyl ketone 16
5 was dispersed in a ball mill for 10 days.Next, 139 g of n-butanol was added to this dispersion and further dispersed for 24 hours. 6g of this dispersion was taken out and a polyvinyl butyral resin solution with a solid content concentration of 0.11% by weight (polyvinyl butyral resin: product name: XYHL manufactured by UCC; solvent: n
-butanol) 23.7 gti-diluted dropwise to obtain a charge generation layer coating liquid (B).

The electrophotographic photoreceptors of Example 1 and Comparative Example 1 obtained as described above were used in a commercially available copying machine (product name: FT4820,
(manufactured by Ricoh) I posted an image of the installation. the result.

In Example 1, a good image with no roughness was obtained even in a halftone image, but in Comparative Example 1, only a rough image was obtained even in a halftone image.

Example 2 A sample was prepared by dissolving 33 g of a charge transport substance shown by the following formula (■) and 36.5 g of polycarbonate resin (trade name: Panlite C-1400, manufactured by Konjin ■) in 316 g of methylene chloride on an aluminum plate. The charge transport layer coating solution prepared above was applied by dip coating, and then heated and dried at 130° C. for 20 minutes to form a charge transport layer having a thickness of 20 pa.

Next, the charge generation layer coating liquid (A
) was spray-coated, heated and dried at 120°C for 20 minutes,
Film thickness 0. An electrophotographic photoreceptor of the present invention was prepared by providing a charge generation layer of IIm.

Example 3 Alkyd resin used in Example 2 (Beccolite 640
An electrophotographic photoreceptor of the present invention was prepared in the same manner as in Example 2, except that Veracolite 52-51114 (manufactured by Dainippon Ink & Chemicals) was used instead of Example 1-50).

Comparative Example 2 A sample was prepared in the same manner as in Example 2, except that the charge generation layer coating liquid (A) used in Example 2 was replaced with the charge generation layer coating liquid (C) below.

[Coating liquid for charge generation layer (C)] Disazo pigment! ! 14.3g of Ill and 165g of methyl ethyl ketone were dispersed in a ball mill for 10 days.Next, 139g of n-butanol was added to this dispersion, and further 24.
Spread out time. Take out 6 g of this dispersion, and take out a melamine resin solution with a solid content concentration of 0.11% by weight (melamine resin: trade name: Varnish-Perbeckamine G-821-60, manufactured by Dainippon Ink & Chemicals, solvent: n-butanol).23. 7g
was diluted dropwise to obtain a charge generation layer coating liquid (C).

Comparative Example 3 A sample was prepared in the same manner as in Example 2, except that the charge generation layer coating liquid (A) used in Example 2 was replaced with the charge generation layer coating liquid (D) below.

[Coating liquid for charge generation layer (D)]

First, 14.3 g of the disazo pigment Nal and 165 g of methyl ethyl ketone were dispersed in a ball mill for 10 days. To this dispersion, 139 g of n-butanol was added and further dispersed for 24 hours. 6g of this dispersion was taken out and the solid content concentration was 01.
23.7 g of alkyd resin solution (alkyd resin: trade name: Beccolito 6401-50, manufactured by Dainippon Ink & Chemicals, solvent: n-butanol) was added dropwise to dilute it, and a coating liquid for charge generation layer (D) was prepared. And so.

Examples 2 and 3 and Comparative Example 2゜3 obtained as above
Electrophotographic photoreceptor was charged with ÷6KV corona discharge for 20 seconds using a commercially available electrostatic copying paper tester (Kawaguchi Electric Seisakusho Model GSP428), and then left in a dark place for 20 seconds. Measure the surface potential Vo (volt) of the photoreceptor, and then apply tungsten lamp light to the surface of the photoreceptor with an illuminance of 4.5.
(looks) and the surface potential is Vo
Find the time (seconds) until the time reaches 1710, and calculate the exposure amount El
/10 (looks/second) was calculated. Table 1 shows the results.
Shown below.

Table-1

Claims (1)

[Claims] (1) In a functionally separated electrophotographic photoreceptor in which at least a charge generation layer and a charge transport layer are laminated on a conductive support, an alkyd resin and a melamine resin are contained as a binder in the charge generation layer. An electrophotographic photoreceptor featuring: